Dendroclimatic Characterization of Southwestern Paleoclimate During the Past 2000 Years

迪恩博士和格雷比尔博士将继续他们的树状气候学工作，重建美国西南部过去的气候。由于树木年轮的大小和形状受到降雨量和其他环境变量变化的影响，因此可以利用它们来重建过去的气候变化。此外，由于年轮是按年存放的，因此可以对这种变化进行准确的年代测定。迪恩和格雷比尔博士将通过分析亚利桑那州、新墨西哥州、犹他州和科罗拉多州活着的树木的额外核心，来增加已经相当可观的数据库。他们的初步工作显示了大约在公元1300年的主要气候波动；这与西南地区的重大文化变革时期相对应。亚利桑那州的团队将把注意力集中在这个问题上。他们将重建降水、温度、生长季长度、帕尔默干旱严重程度指数和河流流量变化的年度和季节变化。在拉美裔时代之前的美国西南部，复杂的文化兴起，涵盖了几个州的大部分地区。这些考古建筑群随着时间的推移而扩大和收缩，最大的考古建筑群在西班牙人到来之前解体。考古学家假设，这些文化变化实际上是对环境变化的反应，西南地区提供了一个极好的变化和人类反应。树木年轮数据将对这类分析有很大帮助。这项研究不仅对考古学家，而且对古生态学家和对气候动态和变化感兴趣的科学家都很重要。今天如此令人担忧的温度和降水的变化在过去发生过多次。重要的是理解它们，并了解人类社会是如何回应的。

Drs. Dean and Graybill will continue their dendroclimatological work to reconstruct past climates in the United States Southwest. Because the size and configuration of annual growth rings in trees are affected by changes in rainfall and other environmental variables, it is possible to use them to reconstruct past climatic change. Also, since tree rings are deposited on an annual basis, they permit an accurate dating of this change. Drs. Dean and Graybill will add to an already substantial data base through the analysis of additional cores from living trees in Arizona, New Mexico, Utah, and Colorado. Their preliminary work show a major climatic peturbation at approximately 1300 AD; this corresponds to a time of major cultural change in the Southwest. The Arizona team will focus their attention on this issue. They will reconstruct changing annual and seasonal variations in precipitation, temperature, growing season length, the Palmer Drought Severity Index, and changes in stream flow. The Southwestern United States saw the rise, in pre Hispanic times, of complex cultures which covered large portions of several states. These archaeological complexes expanded and contracted over time and the largest disintegrated before the arrival of the Spanish. Archaeologists have hypothesized that these cultural changes were in fact responses to variation in the environment and that the Southwest offers an excellent change and human response. The tree ring data will significantly aid in analyses of this kind. This research will be important not only for archaeologists, but also paleoecologists and scientists interested in climate dynamics and changes. Changes in temperature and precipitation which are of such concern today occurred many times in the past. It is important both to understand them and to learn how human societies responded.